Nu-(2-hydroxyalkyl)-nu-methyltaurine-nu-oxides



United States Patent 3,267,135 N-(2-HYDROXYALKYL)-N-METHYLTAURHNE- N-QXIDES Arno Calm, Pearl River, and Thaddeus .l. Kaniecki, New York, N.Y., assignors to Lever Brothers Company, New

York, N.Y., a corporation of Maine No Drawing. Filed Feb. 111, 1965, Ser. No. 431,982 7 Claims. (Cl. 260-513) This is a continuation-in-part of our copending application, Serial No. 173,377, filed February 15, 1962, now Patent No. 3,171,787.

This invention relates to N-(2-hydroxyalkyl)-N-methyltaurine-N-oxides, alkali metal salts thereof, and methods of preparation. The invention additionally relates to detergent and dentifrice compositions containing N-(2-hydroxyalkyl)-N-methyltaurine-N-oxides and alkali metal salts thereof as active ingredients.

The compounds,

where R is an alkyl group having from 8 to 18 carbon atoms, and M is selected from the group consisting of hydrogen and alkali metals, have been discovered.

The novel compounds of this invention are excellent surface active agents, and are useful in detergent and dentifrice formulations. The N-(2-hydroxyalkyl)-N- methyltaurine-N-oxides show detergency characteristics, both alone and in the presence of conventional builder salts, such as alkali metal sulfates, carbonates, silicates, phosphates, borates, and mixtures thereof. The presence of conventional detergent builders generally improves the detergency of the compositions. Additional components, such as carboxymethylcellulose which improves the dirt suspending properties of the washing solution, may be used. Also, other synthetic detergents, soaps, perfumes, abrasives, foam stabilizers, germicidal agents, coloring agents and the like, may be included in the detergent compositions of this invention. Accordingly, they are useful in dish washing detergents, non-soap bars, soap bars, bars containing mixtures of soaps and non-soaps, shampoos, and to other applications known to those skilled in the art where surface active properties are desired.

As will be noted below, another significant advantage of the compounds of this invention is that the compounds within the series having the best detergent characteristics are those where R has a chain length of 13 to 18 carbon atoms, and can thus be obtained from less expensive raw materials.

The N-(2hydroxyalkyl)-N-methyltaurine-N-oxides of this invention are particularly useful in dentifrice compositions, such as toothpaste. These compounds produce a large amount of foam, and do not lose their foaming power during the normal storage period while the compound is in contact with the other toothpaste ingredients. By comparison, the parent compounds, before conversion to the N-oxide, rapidly lose all ability to form a foam during storage.

The N-(Z-hydroxyalkyl)-N-methyltaurine-N-oxides of this invention are prepared by the oxidation of the corresponding N-(Z-hydroxyalkyl)-N-methyltaurine, according to the following equation:

OH CH RC IHCH I ICHQHZSO M H 02 CH CH; RCIIOI-Ifii CHZCHzSO M H20 R and M having the same meaning as given above. While hydrogen peroxide is the preferred oxidizing agent, others, such as ozone, which have been described in the literature for the conversion of amines to amine oxide may be used.

The N-(Z-hydroxyalkyl)-N-methyltaurine may be prepared with ease from starting materials which are relatively inexpensive and commercially available. A desirable method of preparing these compounds is by the simple addition of N-methyltaurine to a long chain 1,2- epoxyalkane. This simple addition technique produces the desired N-(Z-hydroxyalkyl)-N-methyltaurine, and the reaction product is free from inorganic salts which are diflicult to remove. The preparation of the epoxide starting material may be by conventional methods such as oxidation of the compounds derived from petroleum sources.

The following examples describe the preparation nad characteristics of the compounds of this: invention, and also illustrate their usefulness as active ingredients in detergent and dentifrice formulations.

EXAMPLE I A series of the novel compounds of this invention was prepared according to the following general procedure.

60 ml. of hydrogen peroxide (0.536 mole) were slowly added to a warm alcoholic solution of sodium N- (Z-hydroxyalkyl)-N-rnethyltaurine, prepared by dissolving 0.134 mole of sodium N-(Z-hydroxyalkyl)-N-methyltaurine in 350 ml. of 95% ethyl alcohol. The resultant solution was maintained at 5 0 C. for 24 hours. The excess hydrogen peroxide was then decomposed by placing a 1" x 2" piece of platinum foil into the solution and allowing it to remain there for 2 to 4 days. When gas bubbles no longer formed on the surface of the platinum, it was removed from the reaction solution and the solvent was evaporated off. The last traces of solvent were removed by drying the residue at reduced pressure. The residue was finely powdered and suspended in 200 ml. of acetone. The suspension was warmed to 40 C., filtered and the product air dried. Final drying was for 6 hours in a vacuum oven at 30 mm. and C. Table I lists the compounds prepared with this procedure.

Table I Generic formula:

E R' IJHCHzIl CH2O z-SOaNa o H 0 Where Yield (isolated), R: percent C H 97.5 C12H25- 9 8 C H 98 C H 97.5 CgHm-CmHgq (mixture) C13H27C13H37 (mixture) EXAMPLE II A series of N-(2-hydroxyalkyl)-N-methyltaurine-N- oxides was prepared by the method of Example I and tested for detergency by the Terg-O-Tometer Detergency Test. This test gives an empirical measurement of the amount of soil removed from the fabric under simulated rwashing conditions. Sample swatches of cloth soiled in a standard manner with a standard soil are placed in a miniature washing machine, the Terg-O-Tometer apparatus, and laundered in the presence of a measured amount of detergent and water of a standard hardness. A Terg-O-Tometer apparatus is described in the Journal of the American Oil Chemists Society, vol, 27, May 1950, pp. 153-459. After rinsing and drying, the reflectance of the cloths is measured and compared with the reflectance of the soiled cloths before washing.

In the detergency test referred to herein, the Terg-O- Tometer apparatus was maintained in a water bath adjusted to maintain the temperature of the Washing solution at 120 F. -2 F. The paddle oscillation was brought to ninety complete cycles per minute and the paddle oscillated through a 320" are.

With the agitators in position on the machine, the detergent was added in the desired amount to the washpot of the machine. 1250 ml. of water having a hardness of 180 ppm. CaCO 60 parts magnesium and 120 parts calcium calculated as calcium carbonate) was added. The machine was started and the solution agitated until the detergent was dissolved.

Cloth swatches approximately 4 /2 inches by 6 inches were then added and were washed for twenty minutes, after which the test swatches were removed from the solution and hand squeezed. The washpot was refilled with clear rinse water of the same hardness use-d for washing at a temperature of 120 F.i2 F., and, with the agitators running, the cloths were rinsed for minutes. The cloths were then removed, hand squeezed and ironed dry. The reflectance of the cleaned cloths was measured with the Hunter Refiectometer using the green filter.

The Terg-O-Tometer test was carried out in duplicate. The reflectance values in the table below represent the average of the actual reflectance readings taken from eight cloth swatches. Each of the N-(Z-hydroxyalkyD- N-methyltaurine-N-oxides was evaluated alone and in the presence of tetrapotassium pyrophosphate, a conventional builder. Table II summarizes the results obtained.

Table II Terg-O-Tometer-homologous series of sodium N-(Z- hydroxyalkyl)-N-inethyltaurine-N-oxides of formula:

4% Table 111 Terg-O-Tometer Tests of sodium N-(2-hydroxyalkyl)- N-methyltaurine-N-oxides of formula:

1 Tetrapotassium Pyrophosphate.

EXAMPLE IV Three compounds of this invention were evaluated according to the RAP Mildness Evaluation Test for Detergents. In this test, a 2% aqueous solution of the compound was tested on rabbit skin and the results rated according to the following scale:

MILD-NESS RATING 0No epidermal erosion (very mild). 1-Foci or small patches of erosion (fair mildness). 225% to 50% destruction of epidermis (irritating). 3--Greater than 50% epidermal erosion (very irritating).

Table IV below gives the compounds tested and the R-oH-oHH IoHi-o11zs03Na results of the test.

Table IV Reflectance Readings, Compound Mildness Remarks Hunter Reflectometer Eating with Green Filter 40 Sodium N-(2-hydroxydodeeyl)-N- 0 Epidermis normal. Compound 0.025% by Methyltaurine-N-Oxide.

weight of Sodium N-(Z-hydroxytetradeeyl)-N- 0 Do. Level, 0.05% compound Methyltaurine-N-Oxide.

by weight, pl s 005% Sodium N-(2-hydroxyoctadeeyD-N- 0 D0.

by weight Methyltaurine-N-Oxide. of 'IKPP 1 41.7 43.4 32-2 g3 EXAMPLE v 23:: j? A principal utility of N-(Z-hydroxylalkyl)-N-methyl- @o iium) Dodeeylbenzenesullonate 42. 9 2 46.9 taui-ine-N-oxides is their application as dentrifrice detersii iatiiinaitiziixeaaej2:131:31: 39: 0 gentsh following test Prmdur6 Was e to measure the foaming ability of a toothpaste formulation:

1 Tetrapotassium Pyrophosphate.

EXAMPLE III Sodium N- (2-hydroxyal-kyl -N-methyltaurine-N-oxides were prepared from sodium-N-(Z-hydroxyalkyl)-N-methyltaurines, which were in turn prepared by reacting N-methyltaurine with a 1,2-epoxyalkane mixture in which the alkane portion had, in one case, carbon chain lengths ranging from C to C and in the other case, from C to C The method of preparation described in Example I was employed. These compounds were evaluated by the Terg-O-Tometer Test, both alone and in the presence of tetrapotassium pyrophosphate. The mixed alkyl prod ucts showed slight detergency alone and gave a good-toexcellent response to building. Table III below gives the results of these evaluations.

A 2 gram sample of an experimental toothpaste formulation containing the detergent compound under investigation was introduced into a 50 ml. beaker containing 5 ml. of distilled water. The'toothpaste formulation was as follows:

Where sodium lauryl sulfate was used, it was added at a.

H level of 1.16%, and the glycerine level adjusted to 6.69%.

The toothpaste was thoroughly dispersed by gentle stirring, and the dispersion then transferred to a 100 ml. granulated cylinder. Ilhe beaker was washed with 15 ml. of distilled water and the washings also transferred to the cylinder. The cylinder was then inverted 25 times and allowed to rest for 5 minutes before reading the foam volume.

A toothpaste containing 2% of N-(Z-hydroxytetradecyl)-N-methyltaurine-N-oxide produced a 70 ml. foam volume in this test as compared with a foam volume of 40 ml. obtained with a toothpaste containing a conventional detergent, sodium lauryl sulfate, at a level of 1.16%. No change in the foaming power of the N-oxide toothpaste was noted over a one month aging period, while a similar toothpaste containing N-(2-hydroxytetradecyl)- N-methyltaurine as the detergent, failed to exhibit any foam whatsoever after the same period of storage.

EXAMPLE VI Another important property of toothpaste is freedom from irritation of mucous membranes. A mucous membrane study was made comparing the irritation potential of a toothpaste containing N-(2-hydroxytetradecyl)-N- methyltaurine-N-oxide at a 2% concentration level and a similar toothpaste containing 1.14% of sodium lauryl sulfate.

A small amount of each toothpaste was applied to the vaginal tissue of each of six young adult female rabbits. These were divided into two groups, one for each formulation, placing three animals in each group. The paste was applied for three consecutive days and observations made over seven days for signs of irritation to the mucous membrane. No inflammatory reaction was noticed in either group of rabbits. The experimental paste was determined to be without primary irritation.

EXAMPLE VII The acute oral toxicity of N-(2hydroxytetradecyl)-N- methyltaurine-N-oxide was determined in the following manner:

A slurry containing the tetradecyl compound was force fed into the stomachs of ten mice using a hypodermic syringe and a stomach tube. The slurry contained 1 gram of the compound and 9 cc. of water, and was injected at a dosage of 2 grams of slurry per kilogram of body weight. The average weight of the mice was 25 grams. No deaths were observed after a period of 14 days.

The compounds of the present invention are also of exceptional utility in the preparation of heavy-duty detergent formulations. Because such formulations are commonly used in combination with hypochlorite bleaches, it is important that they exhibit good sudsing and suds stability in the presence of such bleaches.

EXAMPLE VIII Tests were made of the foam formation and foam stability of a heavy-duty powdered detergent formulation in which sodium N-(Z-hydroxytetradecyl)-N-methyltaurine- N-oxide was the principal detergent-active ingredient. The detergent formulation, except for the use of the tau-rine-N-oxide, was a commercial detergent formulation containing tetrasodium pyrophosphate, sodium tripolyphosphate, sodium silicate, sodium sulfate and carboxymethyl cellulose. The taurine-N-oxide was used in the formulation at a concentration of 17.62% by weight.

Using the above described formulation, test solutions were made by diluting the powdered detergent in water at a concentration of 3.59 ozs./ 16 gals.

Foam Formation-15 mins.

Foam Stability5 mins.

Sufficient sodium hypoehlorite bleach was used to provide 200 p.p.m of available chlorine The foam formation and stability was tested in the presence of 0.05% vacuum cleaner dirt.

Laurie isopropanolamide was added at a concentration corresponding to 2.9% by weight of the basic test formulation.

The following are typical heavy-duty detergent formulations which may be used. These formulations, if tested as described in Example VIII, will yield similar improvements in foam formation and foam stability in the presence of a hypochlorite bleach.

Percent N (2 hydroxyoctadecyl) N methyltaurine-N- oxide 10 Tetrapotassium pyrophosphate 20 Sodium xylenesulfonate 2 Water 68 Percent N (2 hydroxyhexadecyl) N methyltaurine-N- oxide 3 Nonylphenol-ethylene oxide Ia'dduct 7 Tetrapotassiurn pyrophosphate 20 Laurie diethanolamide 3 Carboxymethylcellulose 0.5 Water 66.5

Percent N (2 hydroxyalkyl) N methyltaurine-N- oxide 2 10 Sodium tripolyphosphate 15 Tetrasodium pyrophosphate 35 Laurie isopropanolamide 3.0 Carboxymethylcellulose 0.3 Water 10 Sodium sulfate 26.7

Percent N (2 hydroxydodecyl) N methyltaurine-N- oxide 5 Linear :alkylbenzenesulfionate (Na) 3 10 Coconut fatty acid monoethanolamide 3.0 Tetrasodium pyrophosphate 35.0 Sodium tripolyphosphate 15.0 Water 8 Sodium sulfate 24.0

The nonylphenol-ethylene oxide adduct contains an average of 6 moles of ethylene oxide.

'lhe alkyl group is a mixture of C12-C20 alkyl groups.

3 The alkyl portion of the linear alkylbenzenesulfona'te has an average of 12 carbon atoms.

Percent Sodium C C alcohol 3 ethylene oxide sulfate 5 N (2 hydroxytetradecyl) N methyltaurine-N- oxide 5 Tetrapotassium pyrophosphate 40 Coconut monoethanolamide 4 Laurie isopropanolamide 4 Sodium Xylenesulfonate 3 Carboxymethylcellulose 0.3 Water 10.0 Sodium sulfate 28.7

Percent N (2 hydroxyoctadecyl) N methyltaurine-N- oxide 3 C C alcohol-7.5-ethylene oxide 7 Coconut monoethanolamide 5 Carboxymethylcellulose 0.3 Sodium toluenesulfonate 8 Tetrapotassium pyrophosphate 50 Water 26 Sodium sulfate 16.7

100.0 We claim: 1. The compounds OH CH; R-(I)H-CH21J{TCH2'CH2SO31VI wherein R is an alkyl group having from 8 to 18 carbon atoms and M is selected from the group consisting of hydrogen and the alkali metals.

2. N- 2-hydroxydo decyl) -N-methyltaurine-N-oxide.

3. N-(Z-hydroxyoctadecyl) -N-methyltaurine-N-oxide.

4. The sodium salt of N-(Z-hydroxydodecyl)-N-methyltaurine-N-oxide.

5. The compound wherein R is a mixture of C to C alkyl groups.

6. The compound wherein R is a mixture of C to C alkyl groups.

7. The sodium salt of N-(Z-hydroxyoctadecyl)-N-me-tl1- yltaurine-N-oxide.

References Cited by the Examiner UNITED STATES PATENTS 1,944,300 1/1934 Ott et al. 260-513 2,658,072 11/1953 Kosmin 260-513 2,929,788 3/1960 *Freese et al 252-137 3,042,623 7/1962 Greene 252137 3,113,026 12/1963 Sprung 260501 LORRAINE A. WEINBERGER, Primary Examiner.

ALBERT T. MEYERS, Examiner.

M. WEBSTER, Assistant Examiner. 

1. THE COMPOUNDS 